title: Phn and Nag-like dioxygenases metabolize polycyclic aromatic hydrocarbons in Burkholderia sp. C3.
abstract: Burkholderia sp. C3 can transform polycyclic aromatic hydrocarbons (PAHs), a class of ubiquitous pollutants, through multiple pathways, indicating existence of multiple dioxygenases (Seo et al., in Biodegradation 18:123-131, 2006a). Both phn and nag-like genes in C3 were cloned and identified with the DNA sequence alignment and the gene organization in the clusters. When cloned and expressed in Escherichia coli, either the alpha- and beta-subunits of dioxygenase of the phn genes or the ferredoxin-, alpha- and beta-subunits of the nag-like genes transformed naphthalene, phenanthrene and dibenzothiophene but at different rates. The E. coli transformant containing the phn genes transformed phenanthrene faster than that containing the nag-like genes, which was consistent with higher transcription of the phnAc gene than the nagAc-like gene in C3 in response to phenanthrene. 1-Hydroxy-2-naphthanoic acid (1H2NA) and 2-hydroxy-1-naphthanoic acid (2H1NA) (3,4- and 1,2-dioxygenation metabolites of phenanthrene, respectively) were detected in the culture medium of the phn genes transformed E. coli. The concentration of 1H2NA was 262-fold higher than 2H1NA in the medium of the phn genes transformed E. coli. The results suggested that the phn genes play a major role in 1,2-/3,4-dioxygenation and 3,4-dioxygenation dominates. Twenty-eight PAH degradation-associated enzymes including those encoded by the nag-like and phn genes in phenanthrene-grown C3 cells were identified via alignment of amino acid sequences of the detected polypeptides with those in protein databases. The polypeptides were determined with nano liquid chromatography-ion trap mass spectrometry after tryptic in-gel digestion of the enzymes on 1D SDS-PAGE.
authors.affiliation: Department of Molecular Biosciences and Bioengineering, University of Hawaii at Manoa, 1955 East-West Road, Honolulu, HI, 96822, USA.
authors.forename: Panlada
authors.initials: P
authors.lastname: Tittabutr
authors.forename: Il Kyu
authors.initials: IK
authors.lastname: Cho
authors.forename: Qing X
authors.initials: QX
authors.lastname: Li
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001673:Biodegradation, Environmental; D019117:Burkholderia / Q000737:chemistry / Q000378:metabolism*; D003001:Cloning, Molecular; D049308:Dioxygenases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004787:Environmental Pollution / Q000517:prevention & control*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D005288:Ferredoxins / Q000235:genetics / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry; D008969:Molecular Sequence Data; D010802:Phylogeny; D010957:Plasmids; D011084:Polycyclic Aromatic Hydrocarbons / Q000737:chemistry / Q000378:metabolism*; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism*; D014169:Transformation, Bacterial
chemical_list: D001426:Bacterial Proteins; D005288:Ferredoxins; D011084:Polycyclic Aromatic Hydrocarbons; D021122:Protein Subunits; D011994:Recombinant Proteins; D049308:Dioxygenases